Re: [RFC PATCH v3] target/ppc: Move system call and rfi instructions to decodetree

[Chinmay Rath <rathc@linux.ibm.com>]

On 7/14/26 03:53, Vishal Chourasia wrote:
> From: Vishal Chourasia <Vishal.Chourasia2@ibm.com>
>
> Moving the following instructions to decodetree specification:
>      sc, scv                         : SC-form
>      rfi, rfid, rfscv, hrfid         : XL-form
>
> This builds upon the previous work that moved mfmsr and mtmsr[d]
> instructions to decodetree.
>
> The changes were verified by validating that the tcg ops generated by
> those instructions remain the same, which were captured with the
> `-d in_asm,op` flag, and also by booting a pseries qemu guest.
>
> This also includes improvements from review feedback:
> - Rename helpers to uppercase (RFI/RFID/RFSCV/HRFID) to match ISA mnemonics
> - Add TRANS_FLAGS_NOT() and TRANS64_FLAGS() macro variants
> - Add REQUIRE_INSNS_FLAGS_NOT() check for flag exclusion
> - Specify lev field as uint8_t in SC instruction format
> - Remove redundant masking in SCV since lev is already 7-bit
> - Replace TARGET_PPC64 ifdefs with REQUIRE_64BIT() macro
> - Gate SC, SCV, RFI, RFID, RFSCV, and HRFID with appropriate flags
> - Replace runtime is_book3s_arch2x() check in RFI with TRANS_FLAGS_NOT(SEGMENT_64B)
> - Consolidate CONFIG_USER_ONLY guards into single block
>
> Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
> ---
> v3: Addressed missing flag checks for RFI and HRFID instructions pointed
> out by Chinmay.
Thanks for taking care of this !
> v2: In v1, do_rfi() path effectively only implemented the instruction
> for user-only and 64-bit builds, so on qemu-system-ppc every rfi was
> translated as invalid. This trapped OpenBIOS in exception return paths
> and caused the boot/tests to hang. In v2 restore the 32-bit system
> emulation rfi path while keeping rfid, hrfid, and rfscv 64-bit-only.
>
>   target/ppc/helper.h                  |   8 +-
>   target/ppc/insn32.decode             |  11 +++
>   target/ppc/tcg-excp_helper.c         |   8 +-
>   target/ppc/translate.c               | 126 ++-------------------------
>   target/ppc/translate/misc-impl.c.inc | 100 +++++++++++++++++++++
>   5 files changed, 126 insertions(+), 127 deletions(-)